This disclosure relates to a tall fescue grass that is tolerant to glyphosate at levels sufficient to remove grass weed species from various turfs. One embodiment of this grass is known as Tomahawk RT (experimental code PST-5MU).
Fescue grasses (Festuca species) are widely used as turf in a variety of applications, including home lawns, golf courses, athletic fields, parks, pasture and along roadsides. Two types of fescue grasses are most commonly grown: tall fescues and fine fescues. Tall fescue grasses (such as F. arundinacea) have excellent drought and wear resistance. Tall fescue is adapted to a wide range of climactic conditions and is the most predominant cool-season, perennial grass in the United States. (See Tall Fescue, Edited by Buckner and Bush, Published by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. ASA Monograph Number 20. 1979. ISBN 0-89118-057-5). The term fine fescue encompasses several sub-types including hard fescue grasses (F. longifolia); these grasses are low maintenance and shade tolerant, but lack the durability of tall fescue grasses.
Glyphosate (N-(phosphonomethyl) glycine) is the active ingredient in glyphosate herbicides, such as ROUNDUP(copyright) brand herbicide produced by Monsanto, St. Louis, Mo. Typically, glyphosate is formulated as a water-soluble salt such as an ammonium, alkylamine, alkali metal or trimethylsulfonium salt. One of the most common formulations is the isopropylamine salt of glyphosate, which is the form employed in ROUNDUP(copyright) brand herbicide.
Glyphosate is a broad spectrum herbicide that inhibits the enzyme enolpyruvylshikimate-phosphate synthase (ESPS). It is conventionally applied as an aqueous solution to the foliage of plants, where it is taken up into the leaves and transported throughout the plant. Commercial formulations of glyphosate may also include one or more surfactants to facilitate penetration of the active ingredient into the plant leaves, as well as compounds to enhance rainfastness. Numerous U.S. patents disclose various formulations of glyphosate, including U.S. Pat. Nos. 4,405,531; 5,118,338; 5,196,044; 5,639,711; 5,652,197; 5,679,621; and 5,750,468.
Little success has been reported in finding natural resistance to glyphosate herbicides in plants. This is beneficial in one respect since it indicates that the likelihood of glyphosate resistant populations of weeds arising is low, but it also means that no naturally resistant desirable plant species are available. As a result, great care must be taken when applying glyphosate herbicides in the vicinity of desirable plants (e.g., crops, ornamentals, grass turf). Glyphosate herbicides are highly effective against grass species and therefore has not been previously known to be effectively applied to control weed growth in turf grasses.
Herein disclosed is a tall fescue which is sufficiently glyphosate tolerate to survive applications of glyphosate herbicides at levels which are sufficient to kill many common grass weeds that grow in fescue plantings. One embodiment of such a glyphosate tolerate tall fescue is termed Tomahawk RT (Tomahawk ROUNDUP(copyright) Tolerant; experimental code PST-5MU). As used herein, a glyphosate-tolerant fescue grass is capable of tolerating application of herbicide effective applications, such as at least about xc2xc pint per acre, such as at least about xc2xd pint per acre, of agricultural grade formulations of glyphosate-based herbicides (such as ROUNDUP(copyright)) brand herbicide produced by Monsanto, St. Louis, Mo.) (equivalent to application of approximately 0.014 g/square meter and 0.028 g/square meter of the active ingredient, glyphosate, respectively). In another embodiment, a glyphosate-tolerant fescue grass is capable of tolerating application of herbicide effective applications, such up to about 1 pint per acre, of agricultural grade formulations of glyphosate-based herbicides (such as ROUNDUP(copyright) brand herbicide produced by Monsanto, St. Louis, Mo.) (equivalent to application of approximately 0.056 g/square meter of the active ingredient, glyphosate) In one embodiment, Tomahawk RT is tolerant to application of least xc2xc pint per acre of agricultural grade formulations of glyphosate-based herbicides (equivalent to application of approximately 0.014 g/square meter of glyphosate). In another embodiment, Tomahawk RT is tolerant to application of least xc2xd pint per acre of agricultural grade formulations of glyphosate-based herbicides (equivalent to application of approximately 0.028 g/square meter of glyphosate). In another embodiment, Tomahawk RT is tolerant to application of up to about 1 pint per acre of agricultural grade formulations of glyphosate-based herbicides (equivalent to application of approximately 0.056 g/square meter of glyphosate). Use of this grass as turf (for example in lawns, on golf courses, in parks, and along roadsides) permits ready control of weeds by application of a glyphosate herbicide. In addition, the Tomahawk RT variety has been observed under growing conditions in Hubbard, Oregon to have a mature plant height from about 120 cm to about 130 cm, a flag leaf height from about 58 cm to about 68 cm, a panicle length from about 19 cm to about 21 cm, and from about 55 to about 86 tillers per 12.7 cm of seeded row.
At least 2500 seeds of the Tomahawk RT variety have been deposited with the American Type Culture Collection (ATCC, Manassas, Va.; ATCC Deposit No.: PTA-2815). Therefore, these seeds are known and readily available to the public.
In one embodiment, the disclosure provides tall fescue plants having the morphological and physiological characteristics of Tomahawk RT, as well as seeds of such plants. In another embodiment, the disclosure provides tall fescue plants having the genotype of Tomahawk RT. The disclosure also encompasses tall fescue plants that are produced by crossing Tomahawk RT with other grass varieties, as well as seeds of such plants. In another aspect, the present disclosure provides a method of producing grass seed, comprising planting seed from Tomahawk RT under conditions that result in the germination of the seed, growth of grass plants and setting of progeny seed, and then harvesting the progeny seed.
The present disclosure also provides a method of producing a glyphosate-tolerant grass plant by crossing a first grass plant with one or more other grass plants to produce progeny grass plants, wherein the first grass plant is a Tomahawk RT variety or a glyphosate-tolerant cross derived from the Tomahawk RT variety, and then screening the progeny grass plants to select a progeny grass plant that is tolerant to glyphosate. Glyphosate-tolerant grass plants produced by this method are also encompassed by the disclosure.
These and other aspects of the present disclosure will become more apparent from the following description.